Lights Definition and 173 Threads

TL;DR Summary: i saw 2 white objects in the dark northern alberta sky i went outside to watch for my uber eats delivery and like i always do i look up to the sky cause im fascinated with astrology.plus this time of year the Aurora Borealis are spectacular. any ways i seen 2 bright lights one...

I have a Christmas tree that's pre-lit. The basic setup is each section of the tree has power, and a strand of wire that comes out and wraps around the tree. That strand passes through a bunch of green plastic connector things, which appear to be a splitter of some sort - the strand goes in...

Apparently, there was a huge CMe that's arriving tonight at 2300EST. Auroras supposed to be visible well into mid States. Lousy time to be in Cuba...

Given values : - Distance between the slit source and the screen L - d1,d2 The problem is to detemine the color of the two lights

If a string of blinking Christmas lights extends from the center of a black hole out to a large radius r. What do I see, if I am perpendicular to the line of lights, at radius r? Experiment specifics 3 solar mass, non-charged, non spinning black hole. Observer is 1,000 Au from the center of...

There are 3 lights in the form of a triangle... A, B, and C are lights and are stationary with respect to each other. S1, S2, S3 are spaceships. B S1 S2 A S3...

I've come across a number of problems in elementary probability theory and statistics that can be exemplified as follows: Naturally, real lamps decay over time, so their lifetimes can't be memoryless. With that being said, is the exponential distribution a good approximation for the...

I was in disagreement with my dad about this and hoped that someone could provide a definitive answer. My take was that a LED driven by a rectified DC power supply will not flicker (provided the rectification is sufficiently smoothed out). Whilst he texted me this, taken from a manufacturers...

In my State, the statute says 2 of 3 brake lights required. How is one brake light any brighter than 3 or 4? Is my perception of reality flawed? & though I say it is just as bright, when asked to give a reason why, I can not produce any answer. Is it because it is simply “there” or is it...

Last night about 2am (checked cctv). The 2001 honda crv car hazard light suddenly turned on in the parking (its that button at the middle above the aircon). When i found out at 7am. The car couldn't start so i connected the jumper, hence asking the question in another thread. Has anyone ever...

There has been a large shift from energy inefficient lighting in the last 10 years to LEDs in domestic, retail stores, cars and council run buildings and street lights. The study in the link below by the French government agency support a previous study in 2012 by Sánchez-Ramos published...

Hello, I looked everywhere and elsewhere for an answer to this. And I can't seem to find an answer. If a High-altitude Electromagnetic Pulse was detonated, Would this set off the Northern Lights? While a solar flair is due to a stream of electrons and ions(I hope that I got that correct). A...

I'm trying to optimize my vein viewer with LED lights but I'm not sure which factors affect the penetration of the light through the skin. (I'm following this guide https://www.instructables.com/id/How-to-make-an-affordable-Vein-Finder-for-use-d/) I can say those factors are the angle of the...

I have a bit of a puzzle I'm trying to answer. A K2 civ decides to celebrate Christmas, so they build a circuit of trillions of Christmas lights 1 LY in circumference. When they flip the on switch, what happens? Do the lights come turn on one after the other in response to the electrical...

First I want to say that I plan to study mathematics and physics in college, so I do not know how a lot of things work exactly since I have not really had a formal physics class. I was wondering if all light moves the same speed, or can some light move faster than other lights for certain...

Homework Statement For a high school physics class, I chose to build a tesla coil for a real world application assignment. I was able to build it fairly easily and it turned out great. Before presenting to the class next week, I've been seeing its effect on different types of light bulbs and...

When we see the aurora moving rapidly are we effectively seeing the Earths Magnetic field moving ? Is that part of the explanation for the morphology of the aurora and why they never look quite the same?

Had a bit of a hard time with this one. Anyone mind giving it a look over? 1. Homework Statement Find the total cost for a business that operates the following for one year. Assume that the rate is 6.4₵/kWh. · Fifteen 100 W light bulbs for an average of eight hours a day. ·...

Homework Statement Hello Everyone, a pleasant good morning to all :) I will attach an image that shows a diagram of a circuit. The question based on this picture is as follows: ''When switch S is closed, the Lamp L, lights. Explain how this occurs.'' Homework EquationsThe Attempt at a Solution...

I have a very nice Christmas electric candlestick that is I can no longer get to work properly. Originally, it came with incandescent light bulbs running in 6 V DC. Some of the lights have burned out, so I looked for replacements and can now only find LED lights. The ones I got are labelled...

A Mystery re Fluorescent Lights I have a fixture F1 from the 1960s with two 2' fluorescent lights B1 and B2. Recently they both began to flicker. A second fixture F2 has a single 2' light B3 which did not flicker. In F2 I replaced B3 with B1. It did not flicker. I then replaced in F2 B1...

I want to wire some LED strips to the bass speakers in my car so that they will light up to the music. I reason that you can't wire the lights in parallel with the speaker because the lights can blow with too much volume. I also read that it will trash the sound quality. ? Anyway, my plan is to...

Attached is a picture of my set-up. It is very simple and if for a car (12V) The LED kit comes with 3 options: Hard wire install, cigarette lighter install, and 9 + 9 V battery demo. The peculiar thing is when I connect the hard wire install plug (shown at the top of the picture) to a...

here "c" is the speed of light , i have a question in my mind and i have no answer for it , if two light beams are moving in opposite directions then their relative speed is simply c using the law of velocities addition in case of special relativity but what if those two light beams are moving...

Hi. I helped my neighbour putting up (quite old, no LEDs) strings of Christmas lights and noted that some of them (different brands) are connected in parallel, others in series. Inevitably, we found several of the serial strings not working due to defective bulbs. We replaced the visibly...

My wife likes the old school bulb look so I picked up some C7 string lights for the tree. This year we got a real tree. I plugged the light string in and after a few minutes the bulbs got so hot I couldn't touch them. Are these things really that safe and ok to put around a tree? I must imagine...

Referring to LEDs as I'm not aware of any other "colour-producing" light, does blue light use more energy than red light? Planck's formula (E=hf) leads me to believe that blue light would drain a battery quicker than red, due to its higher frequency. Surely a device emitting blue light would...

How do the northern lights work? I have already know why it emits light, but why in waves? Why does it move? Are the particles that excite oxygen the ones that were deflected, or the ones that were already heading straight towards the Arctic Circle? Feel free to post any questions as they come...

Since the universe is expanding and all objects are getting farther and farther away from earth, won't there come a time when all of the objects we see will have gotten far enough away from the Earth that we can no longer see them and it will appear to us that the universe has gone dark? In...

Hello all i want to put some led lights onto my motorbike and i just wanted to know that this circuit is correct and yes I've drawn some leds the wrong way round. I want.to use a relay so that the current( even tho should be less than 1amp ) doesn't go though the switch although shoulnt really...

Homework Statement Note - I've asked a very similar problem to this before but I'm redoing it for practice, and this one asks a new question which just ruins everything. I also don't know if I was right the first time yet because I haven't gotten the paper back. Consider a refrigerator whose...

I would like to get an, if possible, detailed analysis of the phenomenon by which you hear a noise in your radio speakers when the home lights are switched off. It probably has to do with a wave packet emitted due to switching off the lights, which is picked up by the antenna of a conventional...

There are 2 traffic lights. Bart knows the probability of stopping at the first light is 40%, stopping at the second light is 50% and the probability of stopping at no lights is 20%. What is the probability of stopping at both lights? What is the probability of stopping for at least one light...

Homework Statement When the filament of a light is broken why do others continue to light? Homework Equations Parallel: U=U1=U2=U3 I=I1+I2+I3+... The Attempt at a Solution Is it because there are some nodes? How can you explain this simply?

Homework Statement When two same lamps are connected with the same battery. Their lighting will be greater when they are connected in series or parallel? Homework Equations Series U=U1+U2+U3+... I=I1=I2=I3... Parallel U=U1=U2=U3... I=I1+I2+I3+... The Attempt at a Solution The answer is when...

Hello, I have a handheld UV mercury vapor lamp, which, when working, leaks some visible light around violet wavelengths. My question is whether it is possible to block violet light but let the UV light using some kind of colored transparent sheets. Thank you..

Okay, so I have completed a practical where I used a light box and then placed different coloured plastics in front of the light and measured the light intensity of each colour. From the results I found that yellow, orange and violet had the highest intensities, with red and green having the...

If I have a contactor that I want to use with two separate control sources, on a site with a single phase power source, is it possible to connect two 120V control signals to the contactor coil, potentially live at the same time and connected to the same source, without causing a short, or...

Ok, so please folks could you advise me which way would be better. I've given a job to build a LED light.the light is a cube shaped lamp which i built myself and put all the diodes in , and now I have to think which way of wiring them would be the best.basically I have 98 red colored 3w led's...

Homework Statement An object is placed between the optical centre and the focus point of a bi-convex lens. The image obtained is always inverted and real. Is this statement true? Justify your answer using the thin lens equation. Homework Equations The Attempt at a Solution

Hello, so I have just learned that CFL bulbs fall into the category of producing UV light, including perhaps some UVB in the case of black lights. I have had a black light bulb and a blue CFL running in my bedroom for almost two years now. I often fall asleep with the lights on, sometimes nude...

Hi! :) This is my first message here. The reason I joined this forum is because there are some knowledgeable people here who might be able to shed some light on an observation that I cannot explain. It happened during the night of July 28, 2013, at around midnight, and it still keeps me...

Homework Statement A total charge of 50 Ah is stored in a 12 V battery of a car. Each of the bulbs of the four parking lights is labelled 3,6 W / 12 V. Homework Equations a) Find the current from the battery when only the parking lights are switched on. b) What is the resistance of one bulb...

I'm not sure this is the intended section for this question, but I couldn't find a better one, so here it goes: Why do lights shine? By this I mean, when you see a light, particularly in the dark, it seems to have lines/spikes extending out from it, outside the bounds of the source itself...

Is there a way to combine lights that are not visible to our eyes and make them part of the visible spectrum?

Hi everyone, So, I am involved in a solar project for the developing world involving solar lights. What I would like some confirmation on is how to figure out how bright a LED light is going to be? I need the light to be bright enough for a child to study by, but unsure how to ensure this...

Homework Statement Need to design a system where the lamp (output) turns on when sound is heard and turns off after 10 seconds of no sound, but it must also be dark (light sensor).Homework Equations The Attempt at a Solution I have put a Light Sensor (that is set to let current flow when it is...

When we turn a light on a wave of high frequency EM waves are emitted, however as soon as we turn the light off the light fades. Why is this? If we were to do the same thing in a perfectly reflecting room (perhaps a spherical room with mirrors on the walls) will the same occur?

Hi, I'm trying to understand how neon lights work. I understand that the emitted light comes from excited atoms in the gas, and I know what a neon light consists of. But I'm a little bit confused about one part, how do the atoms get excited? I've seen two different explanations, if I understand...

Scientists find near-definitive list for rare "earthquake lights" Scientists find records of rare 'earthquake lights' http://www.usatoday.com/story/news/nation/2014/01/02/earthquake-lights-rare-phenomenon/4255097/